The Auschwitz convent is a recurring theme in the campaign against the Islamic center; Newt Gingrich found the analogy impressive enough to post it to Twitter.
The comparison is stupid and abominable, even if you make it in more than 140 characters. Lower Manhattan is not Auschwitz. Also the dispute over the convent at Auschwitz was a complicated one, having to do with a clash between the Poles and the Jews over the understanding of history, made worse by the anti-Semitism and propaganda of the Soviet bloc. But that is beside the point. Lower Manhattan is not Auschwitz.

Auschwitz was a factory complex built for industrialized mass murder. More than a million people were slaughtered there. The gold fillings were melted from their teeth for salvage. People were vivisected, tortured, starved, and gassed. It was a place whose only meaning was deliberate depravity and evil.
If Charles Krauthammer and Newt Gingrich think there is any comparison between what happened at Auschwitz and what happened at Ground Zero, then they are Holocaust deniers. Build 400 sets of Twin Towers, force an entire population into them at gunpoint, and then crash 800 airplanes into them—airplane after airplane, loaded with women and children, with the goal of exterminating their entire race—and you might begin to have something like Auschwitz.